The present invention relates to the manufacturing of torque converter components.
Torque converters typically have components with complex contours. Such components might include, for example, a turbine shroud, an impeller shroud, and a turbine shell. These parts may also include slots through their surfaces, in addition to the complex contours. The current process of making slotted shrouds and shells requires at least two operations. The first involves taking a generally flat blank and putting it through progressive dies (typically eight to eleven stations) to form the contours of the shroud or shell.
FIG. 5 illustrates a sample of progressive die tooling used to form a contoured part, with the top portion of the figure being a schematic view of the progressive die assembly 18 and operation performed at each die station, and the bottom portion illustrating the particular feature being created in the part 19 at that particular station. Station 1 illustrates the first operation, which is a punch and form operation. The first die 20 punches a center hole 22 in the part and locating holes 24. Station 2 illustrates a die 21 for forming a center contour 26 and trimming an edge 28 of the part. Station 3 illustrates additional forming of the center contour 26, and trimming a different portion of the part edge 28. Station 4 further forms a center contour 26, and starts to form a torus shaped ring 30 about the part. Station 5 illustrates a trimming operation about the edge 28 of the part. Station 6 illustrates a forming operation for deepening the torus ring 30. Station 7 re-strikes the same torus ring 30 as in station 6 to further shape the part. Station 8 illustrates the final stamping operation to produce a blank part. One will note, however, that after leaving station number 8, the part, while having all of the contours, does not have any of the slots.
A second operation is then required. The part, now with all of its contours, is then placed in a dedicated slotting machine or dedicated press to form rows of slots in the contoured part. The difficulty is that the slotting machine must be configured to cut the slots into a part that already has complex contours. These slotting machines employ dedicated indexing pierce dies to form the slots by indexing the part as it pierces one slot per row. There can be, for example, 27 slots per row. Thus, it can take a significant amount of time to form the slots in each part. Moreover, not only do these machines have very slow cycle times, they are also very expensive due to the cost of the indexing pierce dies. The indexing pierce dies for dedicated slot cutting machines can take four times longer to obtain than dies for stamping machines, and can cost as much as ten times more to manufacture as do dies for stamping machines. This second operation also adds significantly to the floor space required in a plant due to machine size and the additional machines required to meet volume capacity. Further, slotting inventory space is required to locate the inventory while awaiting the slotting process. In addition, this type of machine is mainly dedicated equipment, which requires significant time and expense to convert for a different use.
Of course, the advantage to cutting the slots after forming is that, since the part already has its complex contours, the slots can be cut to the exact shape and at the exact location desired. One cannot cut these exact desired shapes into the stock material and then run the stock through the dies because the shape of the slots will then change as the material is formed into its complex shape. They will stretch, warp and move relative to the desired position in the finished, contoured part.
Others have attempted to eliminate the requirement for a separate slotting machine operation. They have tried to pierce the slots in a progressive die, without any success, by using complex cam dies to pierce the slots in the last station of the progressive die (after the complex contours of the part have all been formed). However, complexity, die life, cost, downtime, maintenance and reliability issues associated with cam dies were significant and not very cost effective. Consequently, a separate slotting operation is still used to manufacture these components.
Thus, it is desirable to be able to form the slots into a stock material for a torque converter component such that, when formed, the slots on the finished, complex contoured part will be the desired shape and at the desired locations, without requiring an undesirable second operation to form the slots after contouring the component.